1. Field of the Invention
The present invention generally relates to a plasma display panel, and, more particularly, to a plasma display panel, designed to reduce phosphor damage and to have enhanced light emitting efficiency upon discharge.
2. Description of the Related Art
Recently, plasma display apparatuses employing plasma display panels (PDPs) have been spotlighted as substitutes for cathode-ray tube display apparatuses. Such PDPs generally comprise two substrates having a plurality of electrodes formed thereon, a discharge gas sealed in a space between the substrates, and phosphors arranged in a predetermined pattern. When a discharge voltage is applied to the plurality of electrodes, the discharge gas is excited into plasma. Ultraviolet rays emitted through an ionization phenomenon of the plasma cause the phosphors of the predetermined pattern to be excited, thereby providing a desired image.
The PDPs can be classified into AC-type PDPs and DC-type PDPs according to their discharge manner. In the DC-type PDPs, the electrodes are exposed to a discharge space in a plasma state, so that conduction current directly flows through the corresponding electrodes. On the other hand, in the AC-type PDPs, at least one electrode is embedded in a dielectric layer, and discharge occurs by virtue of electric field of wall charges, instead of direct conduction of charges between corresponding electrodes.
FIG. 1a is an exploded perspective view schematically illustrating a conventional PDP, and FIG. 1b is a cross-sectional view of the conventional PDP shown in FIG. 1a. For convenience of description, FIG. 1b shows a lower panel 60 rotated 90°.
Referring to FIGS. 1a and 1b, the PDP 10 comprises an upper panel 50 for displaying an image, and the lower panel 60 coupled in parallel to the upper panel 50. The upper panel 50 comprises a front substrate 11, and sustain electrode pairs 12, each including a scanning electrode 31 and a common electrode 32 disposed in the front substrate 11. The lower panel 60 comprises a rear substrate 21, and address electrodes 22 disposed on the rear substrate 21 so as to lie across the sustain electrode pairs 12. Both the scanning electrode 31 and the common electrode 32 comprise a transparent electrode 31a or 32a formed of transparent ITO, and a bus electrode 31b or 32b formed of a metallic material. The scanning electrode 31 and common electrode 32 pair and the address electrodes 22 lying across the scanning electrode 31 and the common electrode 32 pair constitute a discharge region as a unit discharge cell.
Moreover, a front dielectric layer 15 and a rear dielectric layer 25 for embedding the respective electrodes therein are formed on the front substrate 11 and the rear substrate 12, respectively. A transparent protective film 16 typically formed of MgO is formed on a rear side of the front dielectric layer 15, and partition walls 30 are formed on a front side of the rear dielectric layer 25 for maintaining a discharge distance and preventing electrical and optical cross-talk between the discharge cells. Red, green and blue phosphors 26 are applied to opposite sides of each partition wall 30, and on an upper surface of the rear dielectric layer 25. Meanwhile, an inert mixing gas, such as Ne, Ar, Xe and the like, are sealed in a discharge space between the partition walls 30.
Upon operation of the PDP, as a driving voltage is applied to the sustain electrode pairs 12, surface discharge occurs in the discharge region under the transparent protective film 16. In such surface discharge, ultraviolet radiation is generated by virtue of the ionization phenomenon of the plasma. The ultraviolet radiation excites the surrounding phosphors 26, whereby visible light is generated, and provides a desired image.
In such a conventional PDP, there is a problem in that the phosphors 26 are damaged and then deteriorated due to collision of ions caused by the plasma generated upon the discharge. Moreover, due to the sustain electrode pairs 12 extended in a strip shape (especially, due to the bus electrodes 31b and 32b), it is difficult to secure a sufficient aperture ratio, thereby reducing light emitting efficiency. Additionally, since the upper panel 50 is provided with the front substrate 11 together with the front dielectric layer 15 for allowing the sustain electrode pairs 12 to be embedded therein, the overall transmittance of the upper panel 50 is lowered. Thus, in order to prevent the transmittance of the upper panel 50 from being lowered, the rate of dependency on materials for the sustain electrode pairs 12, the front dielectric layer 15 and the front substrate 11 is increased.
In order to prevent the phosphors from being damaged due to the plasma upon operation of the PDP, Japanese Patent Laid-open Publication No. (Hei) 2004-179099 discloses a method for applying a phosphor-protecting film consisting of SiO2 as a main component on a surface of the phosphor. However, according to the method of the disclosure, it is difficult to uniformly apply the phosphor-protecting film to the phosphor, and an additional discharge gas must be used for facilitating passage of ultraviolet radiation through the phosphor-protecting film.